1. Field of the Invention
The present invention relates to supported coprecipitated metal-aluminum catalyst wherein the metal is selected from the group consisting of the non-ferrous metals of Group VIII of the Periodic Table of Elements. These catalysts are useful in hydrogenating organic compounds.
2. Description of the Prior Art
The catalytic reduction of organic compounds in the presence of one or more metals of Group VIII of the Periodic Table of the Elements, particularly nickel and cobalt as well as nickel-cobalt or nickel-cobalt-copper catalysts is known. For example, U.S. Pat. No. 3,320,182 teaches the preparation of a coprecipitated catalyst by slowly adding ammonium bicarbonate to an aqueous solution containing nickel nitrate and aluminum nitrate at elevated temperatures. These catalysts are taught to have a reduced nickel surface area of 20-30 m.sup.2 /g of catalyst. The coprecipitation of nickel salts from an aqueous solution seeded with porous silica or porous alumina is taught in U.S. Pat. No. 3,371,050. This '050 patent discloses a precipitation process wherein nickel nitrate is precipitated from an aqueous solution containing either porous silica or gamma alumina particles. Example 10 of the '050 patent discloses the coprecipitation of nickel and silicate ions from an aqueous solution seeded with porous silica. Example 11 of the '050 patent teaches that the addition of copper salts to the aqueous solution will promote the nickel catalyst in Town Gas production. The nickel surface area of such catalysts is disclosed as ranging from 40-60 m.sup.2 /g of catalyst.
D. J. C. Yates, W. F. Taylor and J. H. Sinfelt (J. Am. Chem. Soc., 86, 2996 [1964]) described a chemisorption technique and its utility in correlating nickel particle size (and/or nickel surface area) with catalytic activity. In FIG. 3 of their publication, there is shown that a direct relation exists between reduced nickel surface area (m.sup.2 /g of catalyst) and initial reaction rate for ethane catalytically converted into methane (as mmols C.sub.2 H.sub.6 converted per hour per gram of catalyst). It follows, then, that methods which increase the nickel surface area of a nickel catalyst (other factors such as nickel content remaining constant) is a desirable feature, leading to a catalyst of improved catalytic activity. Patentees of U.S. Pat. Nos. 3,697,445; 3,859,370 and 3,868,332 also appreciated that by achieving a higher degree of dispersion of nickel in the catalyst results in a more active catalyst and indeed they obtain a fairly high degree of dispersion by their coprecipitation techniques wherein nickel cations were gradually precipitated from an aqueous solution in the presence of silicate anion and solid porous particles to obtain dispersion greater than 70 m.sup.2 /g of reduced nickel metal per gram of catalyst. Belgium Pat. No. 841,812 teaches that the addition of copper ions during the precipitation step provides a catalyst that can be reduced at temperatures of approximately 200.degree. C. U.S. Pat. No. 4,088,603 discloses an improved method of activating the coprecipitated nickel-copper-silica catalysts.
A number of patents have disclosed cobalt, cobalt-nickel and cobalt-nickel-copper catalysts, e.g., U.S. Pat. Nos. 3,166,491; 3,385,670; 3,432,443; 3,547,830; 3,650,713; 3,661,798; 3,945,944; 4,014,933 and 4,026,823; and British Pat. Nos. 1,000,828; 1,000,829; 1,095,996; 1,095,997 and 1,182,829. None of these patents, however, disclose coprecipitation of one or more Group VIII metal ions and aluminum ions in the presence of solid porous support particles.
Recently, U.S. Pat. No. 4,113,658 has disclosed a method for the controlled dispersion of metal on a coprecipitated catalyst. For example, nickel nitrate and support particles are coprecipitated by gradually increasing the alkalinity of the aqueous reaction mixture.